Allometric partitioning and the relationship between above- and below-ground plant biomass

Plant size is the primary driver of the biomass allocation pattern for understorey plants in sub-tropical forests.

Annals of Botany The relationship between above- and below-ground plant biomass is of considerable interest to researchers attempting to model global climate change and nutrient cycles as well as those interested in evolutionary organographic relationships across taxonomically and ecologically diverse species. Empirical studies and allometric partitioning theory indicate that plant above-ground biomass scales, on average, one-to-one with below-ground biomass at the level of individual trees and at the level of entire forest communities. However, the ability of the allometric partitioning theory to predict the biomass allocation patterns of understorey plants has not been established because most previous empirical tests have focused on canopy tree species or very large shrubs.

In order to test the allometric partitioning theory further, a new paper in Annals of Botany examines 1,586 understorey sub-tropical forest plants from 30 sites in south-east China. The results support the allometric partitioning theory’s prediction that above-ground biomass scales nearly one-to-one with below-ground biomass and that plant biomass partitioning for individual plants and at the community level share a strikingly similar pattern, at least for the understorey plants examined in this study. Furthermore, variation in environmental conditions appears to affect the numerical values of normalization constants, but not the scaling exponents of the relationship. This feature of the results suggests that plant size is the primary driver of the biomass allocation pattern for understorey plants in sub-tropical forests.

Dongliang Cheng, Quanlin Zhong, Karl J. Niklas, Yuzhu Ma, Yusheng Yang and Jianhua Zhang (2015) Isometric scaling of above- and below-ground biomass at the individual and community levels in the understorey of a sub-tropical forest. Annals of Botany (2015) doi: 10.1093/aob/mcu238